Optical data processing is often thought of as a relatively new and promising discipline. There are those who believe that this field is a product of the science and technology of this last decade. The more knowledgeable shake their heads wisely and are confident that they know that the work really started in the early 1950's. However, the real officianados are aware of many important forerunners of the current techniques of optical processing. These forerunners include the development of the knife-edge test by Foucault, the introduction of the Schlieren system by Tbpler, the theoretical work of Abbe on image formation in a microscope, and the subsequent illustrative experiments by Porter. Perhaps the real classic is the phase contrast microscope invented by Zernike.